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A polyimide (PI)-based flexible bandpass filter is fabricated by self-metallization technology, which covers Wireless Local Area Network (WLAN) of 5.15—5.875 GHz. The measured characteristics indicate the flexible filter under flat state has the return loss of better than 20 dB, the minimum insertion loss of 0.83 dB, a 3 dB bandwidth of 0.725 GHz, and the central frequency of 5.5 GHz. At the same time, the designed filter is measured in different bending and folding conditions. Simulated and measured results are similar whether the filter is under flatting, bending, or folding conditions. Fatigue test and timeliness test are studied to confirm that the filter has stable chemical and mechanical properties. The formed silver layers fabricated by self-metallization technology have good mechanical and electrical flexibility. The designed flexible filter is promised for integration within future flexible electronics.

Granite, an excellent medium for deep geological disposal projects, geothermal systems and geological carbon storage, may be affected by its grain size and pre-existing flaws. Thus, three types of granite specimens with different grain sizes containing two non-coplanar fissures under uniaxial compression were investigated experimentally and numerically. Notably, the ligament angle had more effect on the peak strength than the grain size. With an increasing ligament angle, the angle between the crack and the principal stress did not show an obvious trend for β ≤ 60°, whereas the angle between the crack and the principal stress increased when β ≥ 60°. This trend is similar to that for the peak strength. For the same ligament angle, the angle between the crack and the principal stress increased as the grain size decreased. Based on the micro-structure of the crack surface in the ligament (β = 60°), the hypothesis that a shear crack is more difficult to initiate in coarse granite specimens than in fine granite specimens was presented and verified by experiments and numerical simulations.

A coplanar waveguide flexible filter based on the polyimide substrate was fabricated by self-metallization technology. The measured results indicate that the central frequency of the proposed filter is 2.5 GHz, the minimum insertion loss is −0.71 dB and the return loss is better than −20 dB. To test the conformal characteristics of the filter, bending and folding tests were performed. The test results show that the measured and simulated results are basically the same when the filter is bent and folded. The flexible filter fabricated by self-metallization technology is expected to be one of the components of future flexible wireless communication systems.

Experiments were performed to investigate the seismic behavior of concrete-encased steel cross-shaped (CESC) columns. Four specimens subjected to combined constant axial load and cyclic lateral load were tested to study the effects of the axial compression ratio, the steel ratio, and the loading angle on the behavior (strength, stiffness, ductility, and energy dissipation capacity) of CESC columns. Experimental results suggest that the maximum lateral load increases with an increase in the axial compression ratio, while the displacement ductility decreases, and the stiffness degrades seriously. The maximum lateral load and the displacement ductility increase significantly with an increase in the steel ratio, whereas the stiffness degrades slightly. The maximum lateral load at the loading angle 45° is larger than that at the loading angle 0°, but the displacement ductility at the loading angle 45° is lower than that at the loading angle 0°. CESC columns exhibit good ductility, deformation capacity and energy dissipation capacity. Furthermore, a finite element analysis was also carried out to simulate the behavior of the specimens. The results obtained from the finite element analysis agree well with the experimental results. Compared with reinforced concrete cross-shaped columns, CESC columns show higher lateral bearing capacity and better seismic performance.

This article reports the chemical deposition of silver shells on the surface of micro-carbon spheres. The structure, morphology and composition were characterized by scanning electron microscopy and X-ray diffraction. Carbon spheres were oxidized with concentrated nitric acid and sulfuric acid for the surface hydrophilic modifier. Subsequently Carbon spheres were coupled with KH-550 in order to grafting NH2 groups, which is important to the site-selective deposition of silver during sensitization and activation process. The dispersible Ag/C core–shell composite could be systematically controlled through adding appropriate PVP and adjusting modest pH value in the deposition process. The XRD and SEM results show that the silver particles can completely coat the carbon spheres and the particle size of the silver shell on the surface of carbon core is 24.8 nm.

Analyzing stress distribution of the thin circular quartz wafer subjected the radial force through the ANSYS finite element simulation, as well as the theoretical simulation, this paper designed two integrated quartz resonators with different structures and carried on experiments on force-frequency characteristic of resonators. The experimental results show that the resonators force-frequency characteristic is not only closely related to adding force azimuth, but also the electrode size and position. And when force azimuths are same, integrated resonator with asymmetric structure has better force-frequency characteristic, its force-frequency conversion coefficient could achieve 551.8Hz/N after electrode was evaporated with Au.

This article reports the chemical deposition of silver shells on the surface of micro- carbon spheres. The structure, morphology and composition were characterized by scanning electron microscopy and X-ray diffraction. These result show that: concentrated nitric acid can transform the hydrophily of carbon surface; the application of promoting tin-or silver-containing agents that enhance metallic shell deposition by vigorous redox reaction between Sn2+or Ag+, is important to the site-selective deposition of silver. The resulting thickness of uniform silver shells on the surface of carbon and the crystal size of silver is 24.8nm. Amount of Ag-C core-shell structure composite can be systematically controlled through adding PVP and modest pH value

The ultra-sonic gas atomization (USGA) nozzle is an important apparatus in the metal liquid air-blast atomization process. It can generate oscillating supersonic gas efflux, which is proved to be effective to enforce the atomization and produce narrow-band particle distributions. A double-actuator ultra-sonic gas nozzle is proposed in the present paper by joining up two active signals at the ends of the resonance tubes. Numerical simulations are adopted to study the effects of the flow development on the acoustic resonant properties inside the Hartmann resonance cavity with/without actuators. Comparisons show that the strength and the onset process of oscillation are enhanced remarkably with the actuators. The multiple oscillating amplitude peaks are found on the response curves, and two kinds of typical behaviors, i.e., the Hartmann mode and the global mode, are discussed for the corresponding frequencies. The results for two driving actuators are also investigated. When the amplitudes, the frequencies, or the phase difference of the input signals of the actuators are changed, the oscillating amplitudes of gas efflux can be altered effectively.

The dynamic tensile strength of steel fibre reinforced concrete is experimentally investigated. Cylindrical specimens are first fabricated with three different fibre volume fractions of 0, 0·75% and 1·5%. These specimens are then tested by using the Hopkinson pressure bar technique. Their dynamic tensile strengths are measured under medium strain rate impact. In these tests, the stress histories are recorded by way of the strain gauges symmetrically mounted on the specimen and the post-test fracture modes are photographed. The test results indicate that the superposition of waves induces first compressive stress and then tensile stress. Once the tensile stress reaches its critical value, a spalling phenomenon occurs. Both volume fraction of fibres and strain rate exert a significant influence on the dynamic tensile strength of concrete. Furthermore, the strain-rate-induced enhancement of tensile strength is related to the compressive strength of the concrete matrix.

Using finite element method, models of different element mesh density for the center hole in flat plate were established according to one actual steel plate with central circular hole. The stress concentration coefficients of these models were calculated by means of numerical method. Then the calculated results were compared with the theoretical solution results of Elastic Mechanics. And it was analyzed subsequently that the influences which were caused by different element mesh density on the stress concentration coefficients around the hole in flat plate. The relationship between the element mesh density and the stress concentration coefficients around the hole in flat plate was proposed finally. Results show that the element mesh density for calculation affects the stress concentration coefficients around the hole in flat plate significantly, but the influence is few when the mesh density increases to a certain extent.

This paper investigates the compression strength and the energy absorption of steel fibre reinforced concrete under repetitive impact loadings. Cylindrical concrete specimens are fabricated with 0, 1·5 and 3·0% fibre volume fractions. For each fibre volume fraction, stress–strain curves are measured using split Hopkinson pressure bar tests. Also, post-test photographs are taken for each specimen after each impact. The data collected are used to evaluate the energy absorption and the damage evolution of concrete in compression. The results indicate that damage increases and strength decreases with the increase of impact times. Fibrous concrete is markedly superior to plain concrete in resisting dynamic failure. Furthermore, both impact velocity and fibre volume fraction exert a significant influence on the dynamic response of concrete.

A damage evolution law for porous phenolic composites is developed by using phenomenological point, which along with the improved Johnson-Cook model is then implemented into a finite difference code for one-dimensional strain wave problem. The velocity history of free-face particle is recorded and correlated with the simulated result to evaluate the damage parameters. Good agreement shows that the proposed damage evolution law and spall rule are feasible. Besides, the relationships between the striking velocity of flyer and the spall thickness as well as spall time are investigated. This study provides a methodology to quantify the damage evolution of phenolic composites under impact loading.

Titanium dioxide nanotubes (TiNTs) were fabricated from commercial P25 TiO 2 powders via alkali hydrothermal transformation. Dye-sensitized solar cells (DSCs) were constructed by application of TiNTs and P25 nanoparticles with various weight percentages. The influence of the TiNT concentration on the performance of DSCs was investigated systematically. The electrochemical impedance spectroscopy (EIS) technique was employed to quantify the recombination resistance, electron lifetime and time constant in DSCs both under illumination and in the dark. The DSC based on TiNT/P25 hybrids showed a better photovoltaic performance than the cell purely made of TiO 2 nanoparticles. The open-voltage ( V oc ), fill factor (FF) and efficiency ( η ) continuously increased with the TiO 2 nanotube concentration from 0 to 50 wt%, which was correlated with the suppression of the electron recombination as found out from EIS studies. Respectable photovoltaic performance of ca. 7.41% under the light intensity of 100 mW cm −2 (AM 1.5G) was achieved for DSCs using 90 wt% TiO 2 nanotubes incorporated in TiO 2 electrodes.

Aluminum-doped ZnO (AZO) transparent conducting films were deposited on glass substrates with and without intrinsic ZnO (i-ZnO) buffer layers by a home made and low cost radio-frequency (RF) magnetron sputtering system at room temperature in pure argon ambient and under a low vacuum level. The films were examined and characterized for electrical, optical, and structural properties for the application of CIGS solar cells. The influence of sputter power, deposition pressure, film thickness and residual pressure on electrical and optical properties of layered films of AZO, i-ZnO and AZO/i-ZnO was investigated. The optimization of coating process parameters (RF power, sputtering pressure, thickness) was carried out. The effects of i-ZnO buffer layer on AZO films were investigated. By inserting thin i-ZnO layers with a thickness not greater than 125 nm under the AZO layers, both the carrier concentration and Hall mobility were increased. The resistivity of these layered films was lower than that of single layered AZO films. The related mechanisms and plasma physics were discussed. Copper indium gallium selenide (CIGS) thin film solar cells were fabricated by incorporating bi-layer ZnO films on CdS/CIGS/Mo/glass substrates. Efficiencies of the order of 7–8% were achieved for the manufactured CIGS solar cells (4–5 cm2 in size) without antireflective films. The results demonstrated that RF sputtered layered AZO/i-ZnO films are suitable for application in low cost CIGS solar cells as transparent conductive electrodes.

This paper explores the applicability of a novel meshless method, namely the radial point interpolation method (RPIM), to the numerical simulation of consolidation of saturated soils with anisotropic damage. Firstly, an elastic constitutive relationship for the anisotropically damaged soil is derived. The RPIM is subsequently presented. Then, the damage constitutive equation is implemented into the RPIM code, in which the displacement and excess pore water pressure are spatially approximated by the same shape functions and the time domain is discretized by fully implicit integration scheme. At last, the effect of anisotropic damage on soil consolidation process is explored numerically. The results reveal that the established numerical scheme incorporating the constitutive model with anisotropic damage and the RPIM meshless method is very effective in simulating the soil-water coupling problem with good accuracy. Besides, the effects of the magnitude and direction of anisotropic damage are found to exert significant influences on the evolution of settlement and the excess pore water pressure.

Steel Fiber Reinforced Concrete (SFRC) possesses many excellent dynamic performances such as high resistance to explosion and penetration. In the present study, three types of SRFC specimens with 0.0%, 3.0% and 6.0% (percentage by volume) of ultrashort steel fibers are fabricated and subjected to impact compression tests conducted on 74-mm-diameter split Hopkinson pressure bar (SHPB). Based on the stress–strain curves of different strain-rates, as well as the random statistical distribution hypothesis for SFRC strength, a dynamic damage constitutive model of SFRC composite under compression is proposed. The relations of main parameters with strain-rate and steel-fiber content (volume fraction) are also explored and presented in this paper. It is established that both the volume fraction of steel-fiber and strain-rate of loading exert significant influences on the SFRC strength. The new constitutive model is capable of capturing the fundamental dynamic behaviors of the SFRC composite and its theoretical results are in good agreement with experimental data. (A) Reprinted with permission from Elsevier.

This paper starts with a discussion on the theory of finite deformation and various types strain energy functions of rubber like material, the material parameter of elastic law of Gao[3] is estimated by experiment and numerical simulation. Because there are various types of strain energy functions, a user subroutine is programmed to implement the strain energy function of Gao[3] into the program of MSC.Marc, which offers a convenient method to analyze the stress and strain of rubber-like material with the strain energy function that is needed. Two examples will be presented in this paper to demonstrate the use of the framework for rubber like materials. One is to simulate a foam tube in compression. The other one is to simulate a rectangle board with a circular hole. After numerical analysis, it is proved the numerical results based on Gao model are in perfect agreement with the results based on Mooney model and the estimated material parameters are valid.

This paper proposes a method that can be used to synthesize carbon microspheres with controllable sizes, rich amino groups and oxygen-containing groups. The synthesized materials are portrayed by various methods including SEM, FT-IR, XRD, and EDX. The resulting carbon spheres presented an amorphous characteristic, which displayed a broad range in diameter, high degree of sphericity, and smoothness with amino groups and oxygen-containing groups. Pyknotic and smooth silver shells were deposited on carbon spheres by electroless silver plating. Moreover, it could directly reduce Ag + to Ag in aqueous silver nitrate. These materials can potentially be used as adsorbents for heavy-metal removal from aqueous solutions.

This paper presents a simple method to measure the relative permittivity of glass-epoxy printed circuit boards (PCBs). In this method, the relative permittivity as a function of frequency is measured using an actual PCB. In order to estimate the relative permittivity, the reflection coefficient is measured with a network analyzer. The relative permittivity is calculated by observing the frequencies of the resonant cavity modes. We show that the relative permittivity of an FR-4 sample decreases from 4.3 to 4.2 at frequencies from 300 MHz to 2 GHz.

Using an equivalent-circuit model, frequency-selective surfaces (FSS's) with gridded- and double-square elements have been designed and tested for suppressing the harmonics radiation in microwave power transmission system. It is shown that the angular sensitivity of the frequency response of the FSS arrays can be reduced with a combination of TE- and TM-polarized incident waves or a circularly polarized incident waves instead of a single TE- or TM-polarized incident wave. The FSS arrays have also been measured in a microwave anechoic chamber and a good agreement is obtained between the theoretical calculations and experimental results.

By considering active molecules or ions as a collection of induced oscillating dipoles, we treat the problem of Raman or fluorescent scattering by the active molecules or ions embedded in a single-mode optical fiber theoretically. The analytical expressions and the numerical results for the scattering coefficients and the even–odd mode conversion coefficients of the guided modes are given, based on the method of dyadic Green's functions and on the expansions of the modal fields in terms of the vector cylindrical wave functions. We expect to incorporate the treatments into the analysis of a rare-earth-doped fiber amplifier or a fiber Raman amplifier.

Both of equivalent linear and non-linear site response analyses utilize soil dynamic properties expressed by strain amplitude dependent modulus reduction and damping ratio relations. Most of the non-linear site response methods use Masing rule to define the unloading and re-loading paths that results in overestimated hysteretic damping at large shear strain amplitude. In this paper, site response analyses of a soft clay site under very strong input motions at the rock base are performed using the equivalent linear approach (SHAKE analysis) and a non-linear approach (i.e. program FLAC with a user-defined soil model). A 'generalized Masing rule' was implemented in the user defined soil model to correct the hysteretic damping for the unloading and re-loading stress-strain loops to be consistent with the experimental damping. The non-linear site response analyses, we performed, indicate that, with the hysteretic damping correction, the computed surface acceleration and peak shear stress along the depth do not change significantly compared with those without hysteretic damping correction. But the induced peak shear strains in the soft layers are noticeably different between the case with hysteretic damping correction through the generalized Masing rule and that using the original Masing rule.